An integration method for wireless location using mobile phone built-in sensors and TDOA landmarks

Abstract

Non-line-of-sight (NLOS) signal propagation is the major source of error in wireless Time Difference of Arrival (TDOA) indoor system. Even if enough LMs can be deployed by service providers or system designers, existing methods encounter the problem for location estimation when less line-of-sight (LOS) measurements are detected. In this paper, we propose a new method to solve the problem. The proposed method integrates the user's step length into location estimation in wireless TDOA indoor location systems. The proposed method utilizes the user's step size and counts from mobile phone built-in sensors as reference to detect LOS/NLOS measurements. When less LOS measurements are detected, the previous location and step length are added to the least square (LS) method as a supplementary reference landmark (LM) and distance. Simulations results show that, when less number of hearable LOS measurements is not enough, the user's location is estimated with the supplementary reference LM and distance. Simulation results show that location error over time is reduced in a wireless TDOA location system, compared with the related works, in which NLOS measurement detections are overestimated or underestimated.